A wing of the Prince George's County, Md., Courthouse was evacuated after 40 to 50 people complained of headaches or feeling dizzy Tuesday afternoon.
People began feeling sick around 1:15 p.m. in the Bourne Wing, which is the right side of the building in Upper Marlboro.
Several people told News4's Tracee Wilkins that they smelled something strange as soon as they'd entered the courthouse at 8 a.m., and were angry the wing didn't evacuate until six hours later.
Those people had been given medical checks and were told they could go home.
Prince George's County firefighters are at the scene trying to determine the cause of the incident.